Yield link



E. L. SHAW Dec. 1s, 1945.

YIELD LINK Filed March 4, 1943 4 V 2 Sheets-Sheet l.

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.Inni-TDH Dec. 18, 1945. E. L. sHAwl 2,3915275 f YIELD LINK Filed March4, 1945 sheets-Sheet 2 l HH Q 1 94 I 1, y l l i 70 J' 'mi 1 'V as y 86 I75 Fog.9 9/ (f f a0 76 A E/g/n 1 s/mw am Wd Patented Dec. 18, 1945 STATES .PAT 2.391,2*752` YIELDLmK f ENT., OFFICE Elgin L. Shaw, CuyahogaFalls, Ohio,l assignorto Wingfoot Corporation tion of Delaware Akron,Ohio, a. corpora- Application March 4, isaiasirial No. 477,979

(o1.Y zs'zl) as yvellas superstructures of airplanes under v overloadconditions which might occur in exceptionalcircumstances In fact, it maybe used in any type f of machine, `apparatus or structure whereincertain partsrequire protection against y n excessive Aforces of eithertension or compression.

.Y It will be understood that in order to utilize the physicalproperties of the material in such structures economically, and withminimum weight, in some parts,'stres ses closeto the yield point ofthermaterial must vbleallowedA However, to, meet overload conditions and toprevent Wrecking the structure, a safeguard for its protection-becomes anecessity so thatthe structural stresses can V always be kept withinsafe limits. For that purpose, yield links lof large energy absorbingcapacity are installed which come into operationbefore dangerousstresses in a structure can set up. Yieldn links are known which, whenunder vexcessive tension, slowly` give way, absorbing energy either byfrictional engagement of certain parts lor byV various arrangements ofresistant springs, '.iluidprssure cylinders, or the like. Those types`of'1i`nks,fhowever, are somewhat expensive Vin production, because ofrelatively close tolerances required to obtain yielding at predetermined:f ore's.Y Besides, there are several interdepend- .ent parts'A whichmust be machined to exact dimansions. 'I 'he construction according tothis invention avoids this deciency .and has for its object a @cheaperand simpler production and a more reliably .functioning device. .Vinnotherobject ofthis invention Visrthe easy Vduplication of specimenshaving substantially videnticalphysical properties.

A nother object of this invention is theV emf ploymentof only a, singlepart independent of anyother part of the device which accomplishes theyyielding process and whichzpermits quick lexchangeability of the `yieldmember when its renewal is required. Y

All these objects areV obtained, according to this invention, byemployingacompression type of link of ,the most simple construction. The

yieldable part of this link consists of only a tubi ngn1ade. ofductilematerial like steel, copper,

for its al1oys,` etc., which may be ob- :inneres the market in. mashedtube form' orl which can be easily machined Ato exact and `uni formdimensions with readily reproduceable physical properties of the desiredquality. The

same size tubingmay be used for diierent yield forces by simply changingthe length o f the tube.

Incaseof anoverload the tube buckles at a predetermined vforce anddestroys an energy equal to the force acting upon it times its reductionin length. Brieilystated, the invention nds its Vgreatest utilityjinlinks for transmitting axial forces, either tension o r compression, andwhereinany excess forces so applied are dissipated rby compressive,resistance of a destructible yield member.

Y. yThis construction is especially suitable as a link between anairship main ring and its transverse wire bracing or bulkhead whichseparates adjacent gas cells and which usually is mounted under tension.In the event of unequal gas pressure against vthe `two sides of abulkhead, mostv unfavorable Yin the case of a. totally empty gas cell atone side of it, the radialstresses in the bulkhead, and, accordingly thecompressive 4stressesin the ring structure to which it is attached maybecome unduly high. At a certain limit the yieldingofthese safety linksimmediatelyichecks the increase of the structural forces -to areasonable amount.

Insofar as airplanes are concerned, the fuselage and its attachments maybe protected againstV overstressing due to dangerous landing Ashocks byinserting yield links into some members of the undercarriage. In orderto arrest the yielding process of such safety devices at a certain pointa stop may be provided, if desired. YFor a better understanding -of thisinvention a more detailed description shall be given with reference tothe accompanying drawings, where- Figure v1 is a longitudinalcross-section through oneform of yield link embodying the invention;

Figure 2 is a similar sectional View of a modified construction;

Figure 3 is a side view of the structure vshown in Figure 2;

Figure 'fl is a longitudinal cross-sectional view of a furthermodicationVof the invention;

Figure 5 is a. diagrammatic fragmentary View of a main ring of anairship showing one practical application of this invention;

Figure 6 is a fragmentary longitudinal cross- Y sectional View 0f astrut including this invention;

amount of deflection of the yield member, in case of collapse, may beinserted inside the yield member.

An example of a. practical application of a yield link of thecompression type as shown and described in three modifications isillustrated in Figure 5, in which a bulkhead 60 in a rigid air- `ship(lighter-than-air) is `connected to the ring structure62 of the airshipby means of yield devices II, 36 and 49. Any of these constructions maybe applied. The specimens II and 36, both 0f which extend between thering structure and I6 are pressed against yield member I2, theformer bya rod tension member I8 `passingthrough the abutment I6 and the latterby a tubularitension member 20 forming a guide for the abutment I4. Thetension member I3 is .provided at. one end with a ball 22 fitting :intoa socket 24 and is threaded at its other end which holdslthe nut 26against the abutment I4, whereas: the

` tension member 20 screws with one end; into the `abutnient I6 and toitsA other end is yscrewed a clevis 28. The socket is attached to oneYpart off a structure andthe clevis'28- to the other vpart ofthisstructure to vbe connected. 'Each tension `member forms a guide forthe Vabutment supported by the othertension-mem-ber so that the force'towhich the yield device Vis subjected will always go through the axis ofthe yield'member.

The tension member 2-0 is advantageously pro- `vided with longitudinalopenings 29ffor the purpose of an occasional-inspection of the conditionof the yield member. A stop 30'- concentrically disposed in the devicemay be inserted for restricting the amount "off deflection. of the yieldmember shownbyfdottedi lines in collapsedxc'onfdition.

Figures 2 and 3 'show a modificationvof the above-describedconstruction, designated as a Wholevby the numeral' 36, whichconsistsof` the yield member 'I.2L held` between. abutmentsr 3:8. and

K4lill` by the rod tension 'member t8, of the former construction, andby a lit-bolt tension` member-42 :taking the place ofthe tubulartension. member `Z'IIof Figure 1. The. Uebolt 4:2' i'sanchpredgby nuts414 against the abutment 4:0; and carries in 'its loopL portion a.thimble 4B.: attachedftnf one-,part of a structure, whereasthe, socket'24; inf-which islanchoredv the tension member i585 isfattaehed to, theother part ofathis. structure to; be confnected. The abutment; 3,8` isprovidedl with .grooves 45 through. Which pass; the legsof, the

U-,bolt serving as guidesy for theabutment, thereby keeping'`theabutmentsalways in; proper` alignment and the lforce;acting uljnitheidevice yinfaxial direction. A eencentric, stop'. 3 0 may be inserted inthe device; for limiting, the deflection of thek yieIdmember;

Another modification of this invention is illus- `tiatled in, Figure 4and which is, of the, most" simple,construction, designatedsa whclelby.the

:numeral 49, In` this` case the:v abutments, 50; and

52, the first of which is of spherical shape and fits in tda socket 54of the structure, are'f'orced, against the yield member I2 by asingleltension member passingd, throughthe center of?` vthe yieldKmember and being anchored against the abutment 52v` by af. nut 58.. The.spherical shape .of the abutment EI).` makes ,itpossible orftheyield.link to deflect. angularly,` as showmindotted' lines, and to. adapt,itself. to. they changingl 'directionV of forcesfin that part of the-s'truCture to which, 'the tension member, is attached, Solthat thebulkhead are using the same fitting for attachment of the bulkhead onthe ring structure and, therefore, are directly interchangeable,

Whereas' specimen 49 is disposed Within the ring structure and requiresa different fitting for its seat in A`the structure.

1n Figures 6 and 7 is illustrated a yield device, designated as a wholeby the numeral 66, which is especially adapted for being incorporated instrutsyfor instance, of an airplane undercarriage to protect thesuperstructure against damage.

A. yield member IIl telesooped with two sepa- 'rate strut parts'12 and`14, each of which having within and located some distance fromtheirends,

the strut parts.

lflect-ioniof-the yield member;

a Aiixed abutment 16, is firmlyv united with-these parts againsttheiabutments by the tightening of bolts I8 against flanges Bil securelyfastened to In case it is'desired to limit the amount of deflection ofthe yyieldL member, the

yield member is lprovided inside with two disks 'll- 2and Il'4l of;Which-B2 carries a pin 186 and which can slide int-he disk 84. y*Thisrpi'n has located `at lanyy suitable distance from its free end, a

shoulder 88vv which 'serves' as-a *stop for theV de- K The yieldmemberis'shown in the drawings in' collapsed position` by ber canrbereadilyexchanged.

VA modification 'of the yield ldevice` just described-is illustrated inFigures-"8 and 9 andi i'denti-fied as vanassembly" by the' numeralAr9.I, with the only difference that theanges'ofFigure 46 are replaced by'slioulderringsQZ- and the` bolts tia-lly-a morerunifor'm'compression'ofithe strut.

y rIhese` two constructibn's" andl are Shown byfeXamp-le inFigure 10'Aas a' practical7 applicationpna-n airplaneundercarriage96F attached toal fuselage.

vFroml theforegoing `rdesmjiptibn it will be apparent that this'invention constitutesh a decided improvement 'over' previousconstructions;V since this type of yield device contains on'l'ya singlemember independent of anyotherj'part to'V accompli'shthe` deformationprocess; and the physicai Vproperties of'which can'bgeeasilyduplicated.

Due tol the fact that the yield memberis visible 'from thejoutside itcang-be readily inspected whenever'desiredi A l Having. nowdescribed-'this invention in` detail 'by way of several Aexamplesill'ustrat'edit'A i'st'o be understood*thatI4 have's'hown onlycertainjforms ofj thislinventibn by 4way of illustrationv andv that"manyvariations'may bemade'without'iirany` way no other, but an axial,"force, can. actuponthe.

yield member. A controlstop 3U for limiting'the departing from Athe'spirit 'of- *the* inventionand the scopeof the appended claims;V

'I""claim:' y n p I l. A yielddirik' betweentwo` parts"` comprisingajyieliif "memberfof" tubular' cross-section; Aa rodtensiongmember;connected t'o. one off' saidiparts,

aja-shaped. tension vnii-Ember connected tothe 'other one;oisaid"parts'an'd an abutment-.at-

tached to each one ofthe' freeends ofsaidtenysion members andcompressing said yield mem' ber, the rod tension member passing throughthe U-bolt abutment and the U-bolt tension member passing through therod abutment.

2. A yield member inserted between and extending inside two spaced partsof a rigid tubusaid abutments.

4. A yield member inserted between and extending inside two spaced partsof a rigid tubular member, a xed abutment on the inside of each one ofsaid parts and a sleeve union for uniting said parts by forcing saidyield member against said abutments.

5. A yield member in telesccped relation with v two spaced parts of arigid tubular member, a xedab-utment von each one of said parts, meansfor uniting said parts by forcing said yield member against saidabutments, and a stop within said yield member to control the amount ofyield under buckling condition.

'6. A yield device between two parts comprising a yield member oftubular cross section, and an abutment at each end of said yield member,one

of said parts pressing against one of said abutments and the other oneof said parts pressing against the other one of said abutments, theouter face of one of said abutments being made spherically to permitangular deflection of the yielding device.

'7. A yielding device between two parts, comprising a yield member oftubular cross section,

an abutment at each end of said yield member, one of said abutmentshaving a spherical face fitting loosely into one of said parts and theother one of said parts pressing against the opposite abutment to thustransmit pressurethrough said yield member upon the first one of saidparts and permitting angular deection of the yield device.

8. A yield link comprising a thin-walled metal tube, separate meansengaging with an supporting internally each end of the tube, meansadapt-,- ed to apply compression forces to the separate means and to thetube, said tube resisting without deformation all normal compressiveforces, but failing on overload with an accordion-like folding action,said separate means and the means for applying compression beingpositioned so as not to interfere with the accordion folding of thetube.

9. A yield link comprising a pair of spaced abutments, means mountingthe abutments for movement towards each other, and a thin-walled metaltube gripped against its end faces by the abutments and under all normalaction on the abutments holding them positively apart without yieldingmovement, said tube yielding on overload with an accordion-like foldingaction to allow movement together of the abutments.

10. A yield link between two parts, comprising attachment means adaptedto be secured to the parts, an abutment provided for each one of saidattachment means, a thin-walled tubular yield member seating at its endfaces against said abutments and having both of its walls completelyspaced rfrom said attachment means along its yieldable length, saidmember resisting normal operating forces and buckling to reduced lengthunder excessive operating forces.v

ELGIN L. SHAW.

